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Thursday, March 1, 2001

TAMMAS procedure an alternative to spacers

It has become the standard of practice during a two-stage revision for an infected total knee replacement to remove the implant, place a temporary antibiotic spacer, and at a subsequent date perform a revision. Unfortunately, shifting of the spacer can cause bone loss, and stiffness can occur when the knee is held in continuous extension, said researchers in scientific exhibit 20.

The Temporary Articulating Methylmethacrylate Antibiotic Spacer (TAMMAS) procedure offers a method of custom-making two unconventional spacers, which allow articulation, prevent bone loss, yet do not require a mold. The latter avoids regulation approval and prosthetic manufacturing.

The femoral spacer is created by conforming sterilized foil over the distal femur including all bony defects. The foil is then coated with sterile mineral oil. Antibiotic impregnated cement of 10 mm thickness is applied to the foil. A tibial insert trial is used to mold the cement, forming an articulating surface.

When the cement was hard, the foil was removed, and the spacer fit perfectly on the distal femur, without motion. The insert was covered with foil, mineral oil, and antibiotic impregnated cement, the same thickness of the insert. When the cement hardened, the foil was removed, the spacer trimmed and placed in the knee allowing articulation and approximately 45 degrees of flexion.

The implant does not shift within the knee. The researchers explained "this results from the femoral spacer's interdigitation with the distal femur and its articulation with the tibial spacer. This technique allows motion, touch down weight bearing and preservation of bone stock.

"The TAMMAS procedure is an alternative to conventional articulating spacers, without the use of molds or metal implants. It is simply methylmethacrylate and antibiotics, while utilizing instruments, medications and supplies that already exist at the hospital."

Coauthors of the study are Wayne M. Goldstein, MD; Matthew Kopplin, MD; Robin Wall, PA-C; and Berland Kimberly, CST-FA, all of Illinois Bone and Joint Institute, Park Ridge, Ill.

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Last modified 14/February/2001 by IS